Welltest 104: Surface Data Acquisition

There are many useful applications for surface pressure data instruments, besides those already described. Optimization or surveillance purposes for determining timing for the running or pulling of subsurface pressure recorders or termination of critical #welltests. Surface casing-vent tests can be conducted using the closed-chamber method. Water injection well tests for pressure maintenance monitoring (to keep oil wells producing revenues). Closed-chamber drill stem tests. Testing while under-balanced drilling gas wells (#LNG) (drill ahead,...

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Welltest 104: Surface Data Acquisition

Welltest 104: Surface Data Acquisition

It is common practice in pumping oil wells to use acoustic well sounder instruments (#AWS) to obtain reservoir pressure buildup data without pulling rods and pump. With this method each pressure measurement is tied to a liquid level shot, which becomes the primary input signal. Sparse sample rates and noise (due to inaccuracy of the acoustic shot) are inherent problems. Both deficiencies can severely affect pressure derivative analysis techniques. A number of historical AWS #welltests were reviewed, evaluating only surface casing...

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Welltest 104: Surface Data Acquisition

Welltest 104: Surface Data Acquisition

Electronic surface pressure gauges have several fundamental advantages over acoustic well sounder instruments (#AWS). First, the sampling rate is significantly higher, whereas acoustic instrument sampling rates are controlled by the liquid level nitrogen gas shot frequency. Second, an electronic gauge can be left on, recording data, for a much longer time period than an AWS instrument due to significantly lower power consumption requirements and fixed life of the nitrogen gas supply. Finally, manpower requirements for electronic instruments...

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Welltest 104: Surface Data Acquisition

Welltest 104: Surface Data Acquisition

Valid interference #welltest results can be obtained from water injection wells, flowing oil wells, and pumping oil wells. For this example, pressure buildup data were obtained on a pumping oil well using both an acoustic well sounder and an electronic surface pressure recorder. There was no obvious indication of interference from the #AWS data set which, by nature, was quite sparse. Surface annular (casing) pressure data, on the other hand, clearly exhibited a pseudo steady-state relationship through the late-time region, identifying...

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Welltest 104: Surface Data Acquisition

Welltest 104: Surface Data Acquisition

It appears only logical that surface pressure data could prove useful for interference #welltesting in high permeability gas zones. Valid results have been derived from both producing wells and injection wells. This example illustrates the surface pressure data trace from a gas (#LNG) storage observation well. Subsurface pressures exhibited identical behaviour. Substantial cost savings were realized with future #welltest operations by not requiring expensive electric wireline services for surface readout of bottomhole pressure gauges....

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